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XV OPTIMA MEETING, Montpellier (France), 6-11 June 2016, Abstracts
Full text linkBook of abstract of the XV OPTIMA MEETING held in Montpellier (France) from 6th to 11th June 201
Distribution pattern and richness of endemic plant species in Maritime and Ligurian Alps
No full textIn recent years we made an overview of endemic plants (sunsu lato) of the Maritime Alps (115 taxa representing 3.2 %
of the flora). Ecological preferences and plant life strategies were detected, showing a particular ability of endemics to
colonize habitats with low competition and disturbance characteristics. The comparison with other areas of the
Mediterranean basin appears to show that the Maritime Alps are really a ‘hot spot’ owing to the high total number of
vascular plants and the high number of endemic plants. Subsequently, looking for any focus, centre and area of
endemism, analyses were performed on a presence/absence matrix of 36 vascular plant taxa endemic to the study area.
For each operational geographic unit the number of endemic taxa present was counted. Additionally, the weighted
endemism value was calculated. Areas of endemism were distinguished using cluster analysis and parsimony analysis of
endemicity (PAE). The influence of ecological characteristics and historical factors was evaluated using Multi-Response
Permutation Procedure and Non-Parametric Multiplicative Regression. The Indicator Species Analysis (INDVAL) was
also used to identify the species characterizing the areas of endemism.
Our results point out the importance and location of four main area of endemism within the Maritime and Ligurian Alps
explaining the distribution pattern of endemic plants. These areas are easily interpreted by historical and ecological
factors: the NPMR model indicated that the variation in number of endemic taxa is correlated with the thermoclimatic
belts and the extent of Würm glaciations. No significant relationship was found between the number of endemism and
the soil type. The comparison between the distribution of richness of species and the extension of glaciations, the OGU
harbouring the higher number of endemics were in marginal position from the Quaternary glacial sheets. NPMR didn’t
find models environmental patterns comparing the weighted endemism values
The main focus and centre of endemism of the study area were evidenced inside the Roya Valley areas of endemism.
This territory may be considered as a “hotspot within a hotspot”, and its statistically well supported identification
appears to be very useful for future conservation purposes. Finally, the identification of a “hotspots within a hotspot” as
a sum of the previous elements appears to be very useful for future conservation purposes
Past range dynamics and their relationship with current richness: a study case from the SW Alps endemics
No full textEndemic species are not uniformly distributed across the world but some areas are richer than others. In general, it is widely recognized that past climate changes strongly affected endemic richness and distribution. Endemic species shifted little their distributional range over time, accumulating in the so-called areas of persistence because unable to persist in surrounding areas during adverse periods and to expand their range during favourable ones due to dispersal limitations. According to this expectation, past climate stability was detected as the main driver to endemic richness at global and regional scales. We used palaeoclimatic data and species distribution models to analyse the relative importance of in situ persistence versus migration in explaining the current pattern of distribution and richness at local scale using 100 plants endemic to SW Alps. The mean values of predicted persistence over time were very low in all studied species. The currently known endemic richness was positively correlated with both current potential richness and gained species per cell, while the correlation with past mean richness and stable species was very low. Moreover, currently known endemic richness was positively correlated to velocity of past climate changes and mean annual temperature, and negatively correlated with temperature seasonality. The low in situ values of persistence are consistent with phylogeographical evidences on both endemic and non-endemic plants occurring in the study area, suggesting that species shifted their geographical distribution in order to track favourable climatic conditions. The correlation between current known and potential richness suggests that climate is a major driver in endemic richness at local scale. The relationship between current known richness and gained species suggests that at local scale species composition has changed over time. This finding suggest that at local scale richest areas are not located in climatically stable areas, that albeit may have acted as refugia for single species, but in confluence areas, likely as a consequence of the co-occurrence of species colonizing these areas coming from separate refugia. The positive correlation between endemics richness and past climate change velocity is in line with the high temporal and spatial range dynamic detected by species distribution models and supports the idea that short-distance migrations may have weakened both the importance of glaciations in affecting the genetic patterns of endemics and the importance of climate stability with respect to other factors in affecting endemic richness at local scale. These finding support the idea that dispersal and persistence ability of species may affect the relationship between local and regional species richness and that therefore the relation between endemic richness and explanatory variables is strongly scale-dependent. In order to clarify the past range dynamic of SW Alps endemics and their relationship with environmental variability we are now focusing our study on Lilium pomponium, a species potentially prone to extinction risk because of range loss induced by climate change and spanning across Mediterranean to Alpine climate
Local refugia and environmental heterogeneity: a case study in a Mediterranean mountain system (Southern Alps)
No full textEndemic species are of pivotal importance in biogeography and conservation biology, because they are exclusively distributed in a given area. The regions where several endemic species occur are called centres of endemism and are expected to be characterised by stable and often singular climatic conditions that have enable divergence to accumulate over time. In particular, four non-mutually exclusive hypotheses have been proposed to explain accumulation of endemics in the centres of endemism. In general, areas rich in endemics are expected to have climates that are unusual in the region, to have low intra-annual climatic variation, to have high topographic heterogeneity resulting in a high array of local climatic conditions or to have been climatically stable over time. However, within these regions, endemics accumulate in given areas that consequently have an exceptional concentration of endemic species. Several studies aimed at identifying areas rich in endemism, but relatively few studies have attempted to analyse the environmental determinants behind this richness. Here, we aim at identifying the determinants of endemism richness within a centre of endemism, the Southwestern European Alps. We used distributional data for the endemic plants of SW Alps to explore the patterns of endemism richness to assess how environmental factors contribute to explain these patterns. Our results suggest that near all hypotheses adequately account for patterns of plant endemics richness in SW Alps. In fact, most of the relationships are statistically significant (Table 2) and the explained variance ranges from weak to substantial. In particular, temperature seasonality, velocity of climate change and the standard deviation of slope have the highest effect. Overall, no macro-ecological hypothesis fully accounts for species richness, suggesting that, within endemism centres, factors related to species dispersal ability (e.g., the rate of climate change and the standard deviation of slope) as well as region-specific historical factors combine to influence the distributional pattern of endemism richness
Changes in the Flora on Bergeggi islet (NW Italy) across 100 years
No full textWithin the Mediterranean basin thousands of islets show exceptionally high levels of plant diversity, playing a key role in this important global biodiversity hotspot. In this study, long‐term changes in the flora of Bergeggi, a small islet in the northern Tyrrhenian Sea, were empirically assessed. Species were assigned to two abundance classes (rare and not rare species) for the years 1907, 1970, and 2020; and to three classes of abundance changes over the period 1907‐2020. Regional abundance of declining/extinct species and changes in species abundance were correlated with their morphological and life history traits (life form, perenniality, height, dispersal agent, pollination mode), niche and biogeographic characteristics (habitat specialization, level of endemism, biogeographic origin) and taxonomic group. Floristic change was characterized both in terms of absolute numbers of extinct and existing species and through a measure of relative change in range size. Knowledge of changes in land use and ecological correlates of floristic change made it possible to infer the causes of species change and to identify which traits are associated with species vulnerability. The long‐term biological changes documented in the species assemblage of the Bergeggi islet flora are consistent with the predicted consequences of climate and land‐use changes that have occurred on the islet during the past century
Biogeographic and genetic aspects on the relationship between two endemic Moehringia sp. (Caryophyllaceae) of Provence and Liguria.
No full textThis study analyses twoendemic species of the Southwest Italian and French Alps, Moehringia sp. in order to understand the glaciation's effect on speciationevents and or floristic and ecological patterns
Effects of environmental heterogeneity on phenotypic variations of Lilium pomponium L.
No full textThe results of the traits associated with the interaction plant-insect reveled that in Lilium pomponium the separation of sexual organs varied between individuals and populations. Neverttheless, the proportion of flower showing this separation was significantly higher in sothern groups. This suggests that populations occurring under different climatic conditions are exposed to different to differentenvironmental pressure
Local and regional abundance of exotic plant species on Mediterranean islands: species traits or island attributes?
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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